I. Technical Field
This disclosure relates generally to apparatus and methods for merging a building map or other route map with an access point (AP) map or other transmitter map, and more particularly to applying trajectories, relative to the AP map, through various orientations of the building map to find a best fit.
II. Background
Typically, indoor positioning and routing using Wi-Fi networks may be based on a map that shows both building layout and locations of access points (APs). The maps used for indoor positioning and routing using Wi-Fi may be generated by combining two separate maps: an AP map showing locations of access points (APs); and a building map showing locations of walls, passages, doors, windows, etc.
FIG. 1 shows a typical building map 100 with a floor plan that indicates walls 110, doorways 120, hallways 130, rooms 135 and exits 140. In general, a pathway map including common, set or fixed indoors and/or outdoors pathways may be used, such as a two-dimensional map of a theme park or other complex including common indoor and/or outdoor routes. For simplicity, a building map is used as one example of a pathway map described below and is a specific example of an indoor and/or outdoor two-dimensional map or other pathway map. The pathways of the building map including a floor plan are defined by the walls 110, doorways 120, hallways 130, rooms 135 and exits 140.
FIG. 1 shows a building map orientation marker 150 indicating cardinal direction North, which is shown by an arrow labeled “N”. Orientation marker 150 is shown for informative purposes only and is typically not provided for building maps—such as building map 100. A building map may be provided, for example, by the operator of the venue.
FIG. 2 shows an Access Point map 200 showing the locations of Access Points AP0 210, AP1 220, AP2 230, AP3 240 and AP4 250. In general, a Radio Frequency (“RF”) map shows relative locations of various transmitters. The scale and/or orientation of the RF map is disassociated from the pathway map described above. That is, the scale and/or orientation of the RF map is unknown with relation to the pathway map. The Access Point map 200 is one form of a transmitter map or an RF map. An RF map may also be created from transmissions of cellular base stations, node-Bs, Bluetooth base stations, or a combination of types of transmitters having fixed or semi-fixed transmitters.
In FIG. 2, the AP map 200 is an RF map that show locations of various access points. FIG. 2 also shows AP map orientation marker 260 indicating cardinal direction North, which is shown by an arrow labeled “N”. Orientation marker 250 is shown for informative purposes only and is typically not provided or not accurately provided for transmitter maps or AP maps—such as AP map 200.
FIG. 3 shows heat map 300, which shows RF coverage throughout a facility. As shown in FIG. 3, the areas encompassed by dotted-lines indicate the RF coverage for various access points. For example, as shown in FIG. 3, the RF coverage area 310 may correspond to AP0 210. Similarly, RF coverage areas 320, 330, 340 and 350 may correspond to AP1 220, AP2 230, AP3 240 and AP4 250, respectively. In some instances, heat map 300 may be color coded to indicate the strengths of RF fields at a given point in heat map 300. In some instances, AP map 200 and/or heat map 300 may include an RSSI (received signal strength indication) map and/or an RTT (round-trip time) map. Although, not always provided, AP map 200 and/or heat map 300 may also include geo-location information anchoring at least one of the plurality of access points to the geo-location.
AP map 200 and building map 100 may come from different uncoordinated sources. Moreover, AP map 200 and a building map 100 may not be referenced to the same coordinate system. In some instances, AP map 200 and/or building map 100 may not be geo-referenced at all. A geo-referenced map can provide at least one point on the map defined by a coordinate system such as longitude-latitude point, for example, from a GPS device. A geo-referenced map may also contain an indication of Cardinal direction and/or additional geo-referenced points. Typically, a geo-referenced map from a map vendor contains no AP location information.
In the situations described above, misplacement and uncertainty of AP locations on a combined map showing both building layout and AP locations directly translates to extra position error. Thus, there is a need to place or overlay the APs locations accurately on a building map to minimize errors.
FIG. 4 shows a map of self-locating access points 400 generated using information provided by one or more self-locating APs. In some instances, one or more Self-Locating APs (SLAPs) may be able to separately provide information relating to the relative locations of the APs with respect to each other. For example, as shown in FIG. 4, AP0 210 with coordinates (x, y)=(0, 0) is the origin of the AP coordinate system and the locations of APs 220, 230, 240 and 250, may be given relative to AP 210. In other circumstances, one or more self-locating APs may be able to provide a geo-reference. In other situations, no AP may provide a geo-reference. Moreover, to the extent that a geo-reference is provided, such geo-references may be very inaccurate or uncertain.
In addition to being expensive, both computationally and financially, equipping every access point with a GPS to obtain location information would also greatly increase power requirements. Furthermore, GPS signals may not be reliably detectable at indoor access point locations.
Thus, there is interest in utilizing methods to self-localize the access point with a minimum of additional hardware. Therefore, methods and devices that combine the AP map with the building map and provide both AP locations and location connectivity information (LCI) on a single map using a unitary coordinate system are desired. Such a merged map may be used, for example, for future position determination of various mobile devices.